In agriculture or biogas generation, for example, significant quantities of mixtures of liquids and solids arise, such as (sewage) sludge, liquid manure, or fermentation residue, which must be transported, disposed of, and/or processed. In order to keep in particular transport and storage costs for these mixtures as low as possible, it is known to thicken the mixtures by reducing the liquid portion in the mixtures in a targeted manner. This may be achieved, for example, by at least partial evaporation of this liquid portion.
For thickening via partial evaporation of the liquid portion of a mixture, for example a generic drying device may be used which includes a receiving container for accommodating the mixture, a rotor that is situated with one section of its circumference in the receiving container, and a drive device for rotatively driving the rotor. Such a drying device is known from DE 20 2009 018 720 U1, for example. In the drying device cited therein, the rotor is designed as a blade wheel, wherein due to the rotation of the rotor, several of the blades submerge on a continuous basis into the mixture to be thickened and entrain a portion of it, and the mixture suspended on the blades is exposed to an increased evaporative effect on the section of the circumference of the rotor that is not submerged in the mixture; this evaporative effect is attributed to the large-surface, thin-layered distribution on the blades. This evaporative effect is also significantly assisted by the action of an air stream, which is generated by a blower and which may also be heated, on the mixture that is suspended on the blades.